1. Field of the Invention
This invention relates to microbial insecticides and in particular, to a non-sporeforming bacterial strain for use in insect control.
2. Description of the Related Art
Although numerous effective chemical insecticides have been developed in the attempt to decrease or eliminate undesired insects, there is a continued need for new insecticides. Chemical insecticides are often expensive, and may have toxic effects on humans and other animals other than insects. In addition, some 500 species of harmful insects, the vectors of transmissible diseases prominently included, have become resistant to most applicable synthetic insecticides.
Insects have been found to have natural infections caused by microorganisms such as Bacillus pupillae and B. lentimorbus, which appear to overwhelm the immature stages (grubs) of the Japanese beetle causing them to succumb to slow deaths. Bacillus thuringiensis produces a protein toxin in the form of a crystalline parasporal body, which causes paralysis of the gut, and finally death, of the larvae of many moths, butterflies, and other insects which have ingested the bacteria.
Bacterial insecticides, primarily utilizing Bacillus thuringiensis, have provided a means of controlling insect pests, such as insects of the order Lepidoptera, Coleoptera, and Diptera, in which the problem of resistance to man-made pesticides is one of the most acute. The B. thuringiensis cells are cultivated in large amounts to obtain a sufficient number of crystals, which are sprayed on crops to control the insects. Methods and compositions using B. thuringiensis which have been patented include, for example, the patent of Zaehner et al. (U.S. Pat. No. 5,277,906) for an insecticidal composition containing a carrier used against dipterous insects and a crystalline toxin from an asporous strain of B. thuringiensis; the patent of O'Brien et al. (U.S. Pat. No. 5,244,660) for a method of reducing the occurrence of certain darkling beetles; and other patents utilizing specific strains of B. thuringiensis, for example, U.S. Pat. Nos. 5,286,485; 5,262,160; 5,260,058; 5,211,946; 5,204,100 and 5,185,148.
Most other microorganisms are not known to have specific or substantial insecticidal activity, although it is of course possible that large, concentrated amounts of various substances produced by bacteria, or by any living organism, could be generally or specifically inhibitory to living things. The Enterobacteriaceae, particularly Proteus and Providencia and related microorganisms, while sometimes capable of producing various toxins, are not known to have specific insecticidal activity.
Various Proteus species and the closely related Providencia species are found in decaying matter, soil and water, while others are found in animal infections. Typically Proteus species spread rapidly in a nearly transparent, microscopic film of moisture on the surface of freshly poured agar or other media. This film is due to the actively motile swarming of typical peritrichous forms of Proteus. In contrast, Providencia species form small, discrete and more or less circular colonies.
Whether in context of insect microbiology or, more precisely, pathology, a survey of the technical literature fails to reveal a substantial etiologic relationship that has evolved between the insect hosts and the bacteria of the Proteus type. Applicant is only aware of one record relating to Proteus species, which refers to an ostensibly accidental relationship with the immature stages (caterpillars) of the gypsy moth.
It is therefore an object of this invention to provide an effective, microbial product for the control of insects utilizing a Proteus-like Providencia bacterial strain.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.